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Cisco Discover 1 Module 9 Picture Descriptions
9.0 – Chapter Introduction
9.0.1 – Introduction
Slideshow
Slide one text “Our human network communicates twenty-fours a day, 7 days a week.”
Slide two text “We are constantly working, collaborating, learning and playing over the network. We rely on our networks to be available when we need them, no matter what day or hour.”
Slide three text “It is critical that network connectivity and services be restored quickly in the event of a failure.”
Slide four text ”In this chapter, you will learn how to troubleshoot network failures and how to recognize and correct the causes of common network problems.”:
Slide five text “After completion of this chapter, you should be able to:
- Describe the troubleshooting process
- Describe the utilities used to verify TCP/IP connectivity
- Identify and describe common hardware and connection issues in wired and wireless networks
- Us the troubleshooting process to document problems and interact with a help desk”
9.1 – Troubleshooting Process
9.1.1 – Troubleshooting
1 diagram
Diagram 1, Image
The diagram depicts a man sitting in front of his computer. A speech bubble appears above his head, it say’s, “The network is down. If this problem persists, contact your network administrator.”
9.1.2 – Gathering Information
1 Diagram
Diagram 1, Image
The diagram depicts a woman with a clipboard. The clipboard has the Troubleshooting Information Checklist listed below:
Nature of Problem
End User report - Ticked
Problem Verification Report - Ticked
Equipment
Manufacturer - Ticked
Make/Model - Ticked
Firmware - Ticked
Operating System Version - Ticked
Ownership/Warranty Information - Ticked
Configuration and Topology
Physical and Logical topology - Ticked
Configuration Files - Ticked
Log Files - Ticked
Previous troubleshooting
Steps and Results - Ticked
9.1.3 – Approaches to troubleshooting
3 Diagrams
Diagram 1, Image
The diagram depicts the 7 layers of the OSI model. Looking from the top down they are listed, Application, Presentation, Session, Transport, Network, Data Link and Physical. There are several different structured troubleshooting techniques available, including: Top-down, Bottom-up, and Divide-and-conquer
Troubleshooting Approach Starting at the physical layer or Bottom-up
How it operates: Always starts at the physical layer and works its way up until it finds a faulty layer.
Cases for which it is suitable: More Suited for complex cases.
Advantages/ Disadvantages: It is a slow, but solid approach. When the problem is application (or upper layer) related, this approach can take a long time.
Troubleshooting Approach: Data Link, Network and Transport layers or Divide-and-conquer
How it operates: Based on the circumstances (reported issues) and your experience, you might decide to start at any layer and work up or down the OSI stack.
Cases for which it is suitable: Most suitable when you are experienced and the problem has precise symptoms.
Advantages/ Disadvantages: It approaches the layer of the culprit faster than the other approaches. You need experience to use this approach effectively.
Troubleshooting Approach: Application Layer or Top-down
How it operates: Always starts at the application layer and works its way down until it finds a faulty layer.
Cases for which it is suitable: More suitable for simpler problems or those that are suspected to be application/user or upper-layer related.
Advantages/ Disadvantages: If the problem turns out to be related to lower layers, you have wasted a lot of time and effort at the upper or application layers.
Diagram 2, Image
The diagram depicts a girl with a faulty laptop in her hands. There is a replacement laptop on a desk in another room. If the problem with the laptop cannot be fixed with the troubleshooting procedures commonly used to find faults, replace the laptop with a working one and see if the problem still persists.
Diagram 3, Activity
The diagram depicts an activity in which you have to match the scenario with the type of troubleshooting technique. The troubleshooting techniques are Divide and Conquer, Bottom Up, Substitution and Trial and Error. The scenario’s are listed below:
Braseen is troubleshooting a network connectivity problem. She starts her investigation at the physical medium by checking cable connections and slowly works her way up through the layered networking model to the application software running on the hosts.
Medhat is unable to connect to a site on the Internet. To begin troubleshooting he first tests network connectivity. If that fails he will work his way down the layers to the physical medium. If network connectivity tests succeed he will work his way up to troubleshooting the application software.
Patti is troubleshooting an issue on the network. Based on her past experience with similar situations she assumes the problem is a bad IP configuration and starts troubleshooting with that.
Allan contacts the ISP complaining of issues connecting to the Internet. He is unsure of the problem. The ISP sends a new preconfigured modem to Allan in hopes that it solves the situation.
9.2 – Troubleshooting Issues
9.2.1 – Detecting Physical Problems
Single Diagram
Diagram 1, Image
Four small images one of eyes, one of a nose, one of a hand and one of an ear; the senses you use when you troubleshoot.
The Sense of Sight
Vision is used to detect problems such as improperly connected or poorly constructed cables, including:
• cables which are not connected
• cables connected to the wrong port
• loose cable connections
• damaged cables and connectors
• Use of the wrong type of cable
Vision also allows us to view the condition and function of various network devices with LEDs.
The Sense of Smell
Smell can alert troubleshooters to components which are overheating. The smell of burning insulation or components is very distinct and is a sure sign that something is seriously wrong.
The Sense of Touch
Troubleshooters can use touch to feel for overheated components as well as to detect mechanical problems with devices such as cooling fans. These devices usually create a small vibration in the component that can be detected using touch. The absence of this vibration or the presence of excessive amounts of vibration can indicate that the cooling fan has failed or is about to do so.
The Sense of Hearing
Hearing is used to detect major problems such as electrical issues and the proper operation of cooling fans and disc drives. All devices have characteristic sounds and any change from the normal sounds usually indicates a problem of some sort.
9.2.2 – Software Utilities for Troubleshooting Connectivity
Single Diagram
Diagram 1, Image
The type of question that can be answered by using these utilities.
Five computers in a LAN connected to the internet via a router and a comserver.
Computer 1: application ipconfig, the question that can be answered “Do I have the right IP address and subnet mask?”
Computer 2: application Ping, the question that can be answered “Can I send an IP packet to another host?”
Computer 3: application Netstat, the question that can be answered “What are my active network connections and which TCP/UDP ports are in use?”
Computer 4: application Tracert, the question that can be answered “What route will my packets take to another host and how much delay will there be at each hop?”
Computer 5: application Nslookup, the question that can be answered “What is the IP address of ?”
9.2.3 – Troubleshooting Using Ipconfig
Two Diagrams
Diagram 1, Image
Screen shot of a Windows command line running ipconfig.
Diagram 2, Activity
Packet Tracer Exploration: Using the Ping Command
Use the ipconfig command to examine IP configuration information on a host.
(See your lecturer)
9.2.4 – Troubleshooting Using Ping
Three Diagrams
Diagram 1, Image
Screen shot of Windows command line running the Ping command.
Diagram 2, Image
Screen shot of Windows command line running the help file for the ping command (help options showing entering ping ).
.
Diagram 3, Activity
Packet Tracer Exploration: Using the Ping Command
Use ping to examine end-to-end connectivity between hosts.
(See your lecturer)
9.2.5 – Troubleshooting Using Tracert
Single Diagram
Diagram 1, Image
Screen shot of Windows command line running the help file for tracert.
9.2.6 – Troubleshooting Using Netstat
Single Diagram
Diagram 1, Image
Screen shot of Windows command line running the Netstat command with the –a switch.
9.2.7 – Troubleshooting Using Nslookup
Two Diagram
Diagram 1, Image
Diagram depicts a small network. A local client, a DNS server (dnstest.server., IP address 192.168.254.32) and a computer with the name and IP address of 209.165.200.224. The Local Client using nslookup from a Windows command line sends a DNS Query “” to DNSTEST.svr. which in turn tries to resolve the name to the corresponding IP. It then packages the DNS response “209.165.200.224” and replies to the local client.
Diagram 2, Activity
Hands-on Lab: Troubleshooting Using Network Utilities
Use various troubleshooting utilities to diagnose and correct connectivity problems.
(See your lecturer)
Module 9.3 – Common Issues
9.3.1 - Connectivity Issue
One Diagram
Diagram 1, Image
Common Issues
The picture depicts two hosts connected to an Integrated Router. The Integrated Router is connected to a Cable or DSL Modem, which is connected to the ISP.
9.3.2 - LED Indicators
Diagram 1, Image
LED Indicators
The picture depicts a Linksys WRT300N Router that has the front panel displayed. The picture also gives a brief description of the different indicator LEDs.
Security LED
Indicates the current condition of security settings on the device.
Solid green indicates security is enabled.
Activity LEDs(Wireless, Internet, Ethernet)
Sometimes referred to as link lights, an activity LED is normally associated with a specific port. Normal condition is to flash indicating that traffic is flowing through the port On some devices the rate of flash indicates the speed that the port is operating
**Solid green indicates that a device is plugged into the port but no traffic is flowing. Flashing green indicates the device is plugged in and receiving traffic.
**Amber indicates the device is making adjustments to the way the port is operating.
**No light indicates that nothing is plugged into the port, or there is an issue with the wired or wireless connection.
**exact meaning of colors may vary according to equipment and manufacturer
Power LED
Usually a solid green color.
Indicates power to the device
No light indicates a problem with the power. Check power connections.
9.3.3 - Connectivity Problems
One Diagram
Diagram 1, Image
Connectivity Problems
The picture depicts a Cisco Switch, which has Multiple Different Colored Ethernet Cables plugged into it.
9.3.4 - Troubleshooting Radio Problems in a WLAN
Two Diagrams
Diagram 1, Image
Troubleshooting Radio Problems in a WLAN
The picture depicts a screen capture of the GUI Interface used on a Linksys Wireless Device. The Wireless, Basic Wireless Settings tab is selected, with the Network Mode option set to Mixed.
Diagram 2, Activity
Troubleshooting Radio Problems in a WLAN
The activity involves building a Basic Service Set, which is capable of supporting multiple wireless clients and exploring the effects multiple clients have on bandwidth availability.
9.3.5 - Troubleshooting Association and Authentication on a WLAN
One Diagram
Diagram 1, Image
Troubleshooting Association and Authentication on a WLAN
The picture depicts a Wireless Network. There is a Linksys WRT300N Router, which has a Host connected wirelessly to it, and a Server connected via Ethernet.
The Host is attempting to connect to the network, however is unsuccessful as it has entered the wrong key
There are speech bubbles which say:
Host "I sent you the key. Why can I not connect?".
Router "Sorry, that is not the correct key so i am not going to allow you to connect.".
9.3.6 - DHCP Issues
Two Diagrams
Diagram 1, Image
DHCP Issues
The picture depicts a screen capture of the GUI Interface used on a Linksys Wireless Device. The local Network Tab is selected showing the Address information of the Router, and the starting and ending IP Address range for the DHCP Server.
Diagram 2, Activity
DHCP Issues
Identify which part of the network the problem following associated with. (Wired, Wireless or Both)
1. Improperly configured SSID
2, Improperly configured addressing
3. Inability to ping from STA to wired host
4. Disconnected Ethernet port on AP
5. Improperly configured channel
6. Wrong cable type used to connect AP
7. Defective cable used to connect AP
8. Improperly configured Wireless authentication
9. Wrong wireless mode
9.3.7 - Troubleshooting the ISR to ISP Connection
One Diagram
Diagram 1, Image
Troubleshooting the ISR to ISP Connection
The picture depicts a host connected to an Integrated Router. The Integrated Router is connected to a DSL Modem, which is connected to the ISP.
The picture also depicts a Screen capture of a Command Prompt Window on the local client, showing the results of entering the command ping 10.18.32.12 (Destination Unreachable).
9.4 – Troubleshooting and the Help Desk
9.4.1 – Documentation
1 Diagram
Diagram 1, Image
The diagram depicts a pen and calculator .
9.4.2 – Using Outside Sources for Help
1 Diagram
Diagram 1, Image
The diagram depicts four boxes each outlining the different options available for help with a specific problem. The help options are as follows:
Documentation – Good documentation can save a great deal of time and effort by directing the troubleshooting to the most likely cause of the problem. It can also provide the technical information required to isolate, verify and correct the issue. The documentation provided with many networking devices, however, often does not provide sufficient information to troubleshoot anything except the most basic issues.
FAQ’s – Most manufacturers provide a series of Frequently Asked Questions (FAQ) about there product or technology on their website. Usually based on previous requests for help, FAQ’s are a good source of current information and should be consulted whenever possible.
Internet – With the increase availability of the Internet and development of support forums, troubleshooters can now obtain assistance from people around the world in real time.
Colleagues – Colleagues are a wealth of information; there is no substitute for troubleshooting experience.
9.4.3 – Using the Help Desk
3 Diagrams
Diagram 1, Image
The diagram depicts a woman sitting at a desk acting as the Help Desk contact. A speech bubble appears above her head, it says, “Good afternoon Mrs Smith, Thank you for calling the helpdesk. My name is Pat, how may I be of assistance?” The customer replies, “I cannot connect to the Cisco website.” The helpdesk woman then replies, “In order to help you, I will need to gather some additional information.”
Diagram 2, Image
The diagram depicts a man sitting at a desk acting as the Help Desk contact. A speech bubble appears above his head, the following conversation occurs-
Helpdesk “When did this start to occur?”
Customer “The internet was working fine till 30 minutes ago.”
Helpdesk “Where do you live?”
Customer “East of the river in Dodge City.”
Helpdesk “We are showing a lightning strike in that area, we have a team at the scene so connectivity should be restored within the hour.
Diagram 3, Image
Picture of a woman.
9.5 – Chapter Summary
9.5.1 – Summary
Single Diagram
Diagram 1, Flow Chart
Application (application, presentation, session)
Troubleshooting Approach - Top-down
How it operates - Always starts at the application layer and works its way down until it finds a faulty layer.
Cases for which it is suitable - More suitable for simpler problems or those that are suspected to be application/user or upper-layer related.
Advantages/ Disadvantages - If the problem turns out to be related to lower layers, you have wasted a lot of time and effort at the upper or application layers.
Transport
Troubleshooting Approach - Divide-and-conquer
How it operates - Based on the circumstances (reported issues) and your experience, you might decide to start at any layer and work up or down the OSI stack.
Cases for which it is suitable - Most suitable when you are experienced and the problem has precise symptoms.
Advantages/ Disadvantages - It approaches the layer of the culprit faster than the other approaches. You need experience to use this approach effectively.
Network
Troubleshooting Approach - Divide-and-conquer
How it operates - Based on the circumstances (reported issues) and your experience, you might decide to start at any layer and work up or down the OSI stack.
Cases for which it is suitable - Most suitable when you are experienced and the problem has precise symptoms.
Advantages/ Disadvantages - It approaches the layer of the culprit faster than the other approaches. You need experience to use this approach effectively.
Data Link
Troubleshooting Approach - Divide-and-conquer
How it operates - Based on the circumstances (reported issues) and your experience, you might decide to start at any layer and work up or down the OSI stack.
Cases for which it is suitable - Most suitable when you are experienced and the problem has precise symptoms.
Advantages/ Disadvantages - It approaches the layer of the culprit faster than the other approaches. You need experience to use this approach effectively.
Physical
Troubleshooting Approach - Bottom-up
How it operates - Always starts at the physical layer and works its way up until it finds a faulty layer.
Cases for which it is suitable - More Suited for complex cases.
Advantages/ Disadvantages - It is a slow, but solid approach. When the problem is application (or upper layer) related, this approach can take a long time.
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